1. Field of the Invention
The present invention relates to a boat propulsion device equipped with a fuel tank.
2. Description of the Related Art
A boat propulsion device, equipped with a fuel tank, an engine, and an exhaust pipe, is well-known (see e.g., Japan Laid-open Patent Application Publication No. JP-A-2011-190704). The fuel tank temporarily stores fuel from an outside tank disposed in a hull. The engine includes a fuel injection device that injects the fuel stored in the fuel tank into cylinders. The exhaust pipe is connected to the engine and accommodates a catalyst. When the fuel tank runs out of fuel in the boat propulsion device, chances are that an air-fuel ratio in the cylinders becomes an over-lean state and misfiring occurs. In this case, chances are that unburnt gas, leaking out of the engine into the exhaust pipe, burns by making contact with the catalyst heated to a high temperature, and thus, the high-temperature catalyst is overheated.
In view of the above, Japan Laid-open Patent Application Publication No. JP-A-2014-20354 discloses a technology for a boat propulsion device which is configured to preliminarily detect a fuel shortage in a fuel tank based on a decrease in pressure of the fuel to be supplied to the fuel tank.
However, the boat propulsion device disclosed in Japan Laid-open Patent Application Publication No. JP-A-2014-20354 is required to be equipped with a fuel pressure sensor to detect the pressure of the fuel.